null reference exception on simple implementation

Alex Hedlund 6 posts 55 karma points

Oct 28, 2014 @ 21:46

Null Reference Exception on simple implementation

Hi there,

I've been having issues with this plugin on several Umbraco 7.1.x installations(a 7.1.6 and a 7.1.8 I believe). The backoffice parts of the plugin work splendidly, but I get a NullReferenceException when I try to view a page. I've set a min & max items of 2 & 3 respectively on my data type. Here's a copy of my template (it's just a clone of the front page example)

@using YouTube.Models
@inherits Umbraco.Web.Mvc.UmbracoTemplatePage

@{
    Layout = null;
}

@foreach (var typedVideo in Model.Content.GetPropertyValue("video"))
{   
    @Html.Raw(typedVideo.Player.EmbedHtml)

    @typedVideo.Snippet.Title

    @typedVideo.Statistics.ViewCount

    @typedVideo.Snippet.PublishedAt.Value.ToShortDateString()
}

The error occurs on the @foreach line and prints the following stack trace.

[NullReferenceException: Object reference not set to an instance of an object.]
   ASP._Page_Views_Sandbox2_cshtml.Execute() in c:\inetpub\wwwroot\Umbraco\Views\Sandbox2.cshtml:8
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +279
   System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +124
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +180
   Umbraco.Core.Profiling.ProfilingView.Render(ViewContext viewContext, TextWriter writer) +139
   System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +379
   System.Web.Mvc.<>c__DisplayClass1a.<InvokeActionResultWithFilters>b__17() +32
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) +613
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) +613
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +263
   System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +240
   System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +28
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +15
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +53
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +15
   System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +42
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +15
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +606
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +288

edit: I installed plugin version 1.0.2 build 65. Added new stack trace.

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Dennis Aaen 4500 posts 18255 karma points admin hq c-trib

Oct 28, 2014 @ 22:29

Hi Alex and welcome to our.

I must say that I haven´t try out this package myself, but I would try to help you the best I can.

What I think you are missing is that you need to tell what type of data are gettig back, from the package page example I see that you are missing the <YouTube> after GetPropertyValue

So try this:

@using YouTube.Models
@inherits Umbraco.Web.Mvc.UmbracoTemplatePage

@{
    Layout = null;
}

@foreach (var typedVideo in Model.Content.GetPropertyValue<YouTube>("video")){   
    
@Html.Raw(typedVideo.Player.EmbedHtml)

    @typedVideo.Snippet.Title

    @typedVideo.Statistics.ViewCount

    @typedVideo.Snippet.PublishedAt.Value.ToShortDateString()
}

Hope this helps,

/Dennis

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Alex Hedlund 6 posts 55 karma points

Oct 28, 2014 @ 23:27

Thank you for the kind welcome and help!

That's strange, I thought the return type was there. I fixed that but I'm still having the issue. Here's my new stack trace.

[NullReferenceException: Object reference not set to an instance of an object.]
   ASP._Page_Views_YoutubeTester_cshtml.Execute() in c:\inetpub\wwwroot\Umbraco\Views\YoutubeTester.cshtml:7
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +279
   System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +124
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +180
   Umbraco.Core.Profiling.ProfilingView.Render(ViewContext viewContext, TextWriter writer) +139
   System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +379
   System.Web.Mvc.<>c__DisplayClass1a.<InvokeActionResultWithFilters>b__17() +32
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) +613
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) +613
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +263
   System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +240
   System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +28
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +15
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +53
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +15
   System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +42
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +15
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +606
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +288

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Dennis Aaen 4500 posts 18255 karma points admin hq c-trib

Oct 29, 2014 @ 13:50

Hi Alex,

I have a look on your code once again. I think I spotted what give you the error.

Try to change:

@inheritsUmbraco.Web.Mvc.UmbracoTemplatePage

To this line:

@inherits UmbracoTemplatePage

I have also add a check to check if the property has a value on the current page, if not, then it will not print out, this is a good thing to do if you have e.g a unorded list, or some other HTML around that you only want to print if the field contains a value.

@inherits UmbracoTemplatePage
@using YouTube.Models
   
@{
    Layout = "umbLayout.cshtml";  
}
@if(Model.Content.HasValue("video")){
   
    foreach (var typedVideo in Model.Content.GetPropertyValue("video")){  
       
            @Html.Raw(typedVideo.Player.EmbedHtml)

            @typedVideo.Snippet.Title

            @typedVideo.Statistics.ViewCount

            @typedVideo.Snippet.PublishedAt.Value.ToShortDateString()
    }
   
}

Hope this helps,

/Dennis

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Alex Hedlund 6 posts 55 karma points

Oct 29, 2014 @ 17:44

Hi Dennis,

I figured out the problem using your advice. The string in the foreach statement needs to be the name of the document property (in my case "YouTube") not "video". I used the following template and kept changing things until I triggered the if statement (it also works with you inherits line change).

@using YouTube.Models
@inherits Umbraco.Web.Mvc.UmbracoTemplatePage
@{
    Layout = null;
}

<h2>Precondition test string</h2>
@if(Model.Content.HasValue("YouTube")){
    <h2>If statement triggered</h2>
}

So now that I'm getting return values from Model, I should be able to run the foreach. I updated my old template, and I got a few videos to display on my page!

@using YouTube.Models
@inherits Umbraco.Web.Mvc.UmbracoTemplatePage
@{
    Layout = null;
}

@foreach (var typedVideo in Model.Content.GetPropertyValue<YouTube>("YouTube"))
{   
    <div>@Html.Raw(typedVideo.Player.EmbedHtml)</div>
    @typedVideo.Snippet.Title<br/>
    @typedVideo.Statistics.ViewCount<br/>
    @typedVideo.Snippet.PublishedAt.Value.ToShortDateString()
}

Thank you so much for your help!

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Null Reference Exception on simple implementation